Syntonization of circuits used in wireless signaling



Patented Aug. 17, 1926. I i 1 i v UNIT ED STATES P AT ENT OF FI C E.

I ROBERTCLEMENS'GALLETTI, E MURS, BREGNIER-CORDON, FRANCE.

SYN'J.ONIZA'IION 0f QIIR-C'UZ LTS USED IN WIRELESS SIG.cTALINGfr. No Drawing. Application filed August 23, 1921, Serial No. 494,689, and'i n Italy August 5, 1920.

This invention relates to-the syntonization factor in any Wireless station. See also of circuits used in Wireless telegraphy. Framework of Wireless Telegraphy by 50 Hitherto the practice has been to' tune, or the applicant, printed by Cambridge Unisyntonize, firstly by endeavouring to obtain vcrsity Press, published by Orossby Lock- 5 identity of periodicity by satisfying the ,Wood & Co.

equations (IL-:(YL wherein C C and i "In a given Wireless station K ca-nnotzbe L L are respectively the effective capacities freely manipulated, except by construction 5 and inductances of the circuits and secondal changes of the aerialand earth, but in ly by manipulatinglthe coupling sofar as it appears With the other coefiicients 1c M in exact algebraic relations, it can be determined just as accurately as the other coeffi- 1 1/ cients. v c0 of each station so as to enhance the produc When deslgnlng wll'eless P 1t 13 tion ofthe free oscillations, Without greatly efssential approximately to determine F' 15 impairing the e'fliciency of transformation. hand Value of from comparatlve Th y t i ti a di t tl e'p nesent constructional data, its exact value subseinvention consists in producing a complete l y esmbllshefll each erected slfltlofil 5 accord not only with regard to the frequen- 3 the contmlhng fact 9 the algemimc cies of the inducing a-nd induced currents, lelatlons requllfed b Satlsfied accoidlng but also With regard to the shape of the to the PresenJ6 lnvelltloncurves of the waves d currents) a lt In the above equation, the aerial current on hi h i bt i d b a i l ti th is assumed to be'a continuous function of rious electric constants or coefficients, includ l i a yp t s Whlch 51 b rectified iug the radiation constant, until the alg'ebra- Case Of Wlreless i 'HIS IOII by con i equations h ft dlt are m sidering the distuibance or the equilibiiuin fl d f th purpose f tt i i th f ll after each nterval ortime (Z t of continuous ing results :-pure sinusoidal elementary ual action; that the ac a current f Waves, impulsions of current, double pure U'flllfimlssloll sinusoidal OlmfZLCl/EIBUC roots, triple eX- th (1 0:

" ponential real roots, transformer efiiciency L 17 between aerial-and condenser circuit coupled therewith, perfect accord between Wave functions and transmitting current func- Kz 14 tions, exclusive propagation byea-rth, and T perfect accord between both stations.

a T l b i equations t b t fi d From this follows, inter aha, two facts cording to the present invention are derived 0f practlcal l r i from the following general differential equa- (1) lVherever the general integral of a tion:- conta ns a pure sinusoid, viz, wlthout protd3 gresslvedamplng, e.

i This equation was proved in the article 6 V mblished y me 111 the N110) clment'o of such sinusoid is stopped (current together and the actual Wave reaction: 80

October, 1917, under the title Potenza di with all functions) in a given time) e, g)

radiazione elettrica and contains a new radiation coefficient K which like the other I 92 s 95 coefficients C, L, :R and M is a concrete K by mutual elimination of the main current on and of the sum of infinitesimal currents together will all their functions.

(2) The wave transmitted is composed of infinitesimal elements, each of which is a continuous function such as:

K (2% Y t as (element of aerial current) for each element transmitted.

The facts referred to have also a bearing upon the possibility of wave reception in complete accord and consequently upon the eiiiciency and selectivity of reception, which surpass theresults obtained solely with the reception by means of uniformity of preponderating period.

The invention may now be further elucidated by the following explanation so far as exclusive propagation by earth is concerned:

The intrinsic power of wave surface in real dielectric space is (see page 15 of the Framework of Wireless Telegraphy referred to); consequently the difference between this power and the power that is emitted is the wave surface power in imaginary dielectric space, viz,

in other words, the latter is the imaginary continuation of the real dielectric wave through the centre of propagation.

In wireless transmission by means of an aerial having an earth connection, the latter is the centre and the imaginary dielectric wave becomes real earth propagation; indeed the earth being conductive, it stands for imaginary space with respect to the atmosphere, which is a dielectric.

The receiving aerial at a distance, which is crossed by the expanded shells of propagations transmitted, intersecting for a very small but constant fraction of volume 6 in it, is the seat of a total current (see pages 13 and 1 1 of the booklet referred to) provided that its characteristic equation be identical with the characteristic equation of the transmitting aerial.

Now, the atmosphere is not a perfect dielectric, just as the earth is not a perfect conductor, so that progressive absorption of the wave propagation takes place by either way. However, symmetrical absorption by both ways, air and earth, can only be fortuitous and occasional; consequently permanent reception in perfect accord for great distances of communication requires effective propagation by one way only, that is to say, in our case, the annihilation of the above-mentioned ratio or index of propagation distributed between air and earth:

I have attained this by syntonizing in such a manner as to render negligible as compared with y j 'with regard to the general integral of function for puffs of power emitted.

In view of the wave lengths adopted nowadays for long distance communications, one may say, broadly speaking, that reception in perfect accord beyond 1000 kms. requires single propagation by earth.

In practice it is also required for obtaining complete accord to reduce the emission to one time constant. I have attained this by syntonizing to satisfy a system of char acteristic solutions, viz, by double sinusoidal roots or triple real exponential roots, in contradistinction to the approximate method hitherto used, viz, loosening of coupling and reduction of consuming reactions as compared with the oscillatory reactions of capacity and inductance.

It is further required to have a good transformation efliciency between the aerial and the condenser circuit coupled therewith and by using the method according to the present invention it so happens that the coupling required for most efiicient transformation is the same coupling as that which goes with the double roots.

The invention is carried intov effect by the usual practical means employed in wireless telegraphy, the conditions to be realized be ing expressed by algebraic relations of a definite character,

Thus, assuming the characteristic equations of the aerials oftwo communicating stations to be:

CKgfi+CLy +CRy+1IO CI/I ://y3+O//L/!il/2+C/(RI/y+1:0 their identity is obtained by making CI{:CIII I! cL cf/Llf cRzcllRll In these equations C, L, R and K are respectively the capacity, the self-inductance, the resistance and the radiation co-efiicient of the aerial of the transmitting station and C, L, R and I respectively the capacity, the self-inductance, the resistance and the radiation coeflicient of the aerial of the receiving station.

In order to obtain waves of a single periodicity, I simplify the wave functions by making use of doubleand triple characteristic roots expressed by the equations roi roy o re) =r =1 respectively. p

In order to syntonize a simple aerial represented bythe equation and i I make use of the relations (see page 21 of the Framework of Wlreless Telegraphy above re'lerredito) and pacity, the self-inductance,the resistance and the radiation co-efliclent of the aerlal 'The syntonization of the aerial may also be effected by making use of the relation either combined with the ratio whereby a single impulsive discharge is obtained in the aerial and almost excusively earth propagation or combined with the ratio at times a multiple of 7r, wherebythe emis- S1011 of wave elements 15 obtalnedwhlch have a pure sinusoidal function of stopping and comprised in the arc The syntonization of an aerial and of a condenser circuit coupled therewith, the two being represented by may be effected by the use of the combined relations a c o'a OL=CL M KaQ- leading to the couple of characteristic roots (see page 24 of theTramework of WVireless Telegraphy) whereby an er'iiciency of one is obtained causing the current in the aerial as already indicated above and G, L, R are respectively the capacity, the self-inductance and resistance of the condenser circuit coupled therewith, whilst M is the mutual inductance of the two circuits.

By using the combined relations the coincidence of the group of three roots into one triple root On the other hand, if the relation ii: RCL is used there results, amongst the roots of the group, the couple 1 i /CL whereby an efficiency of one, viz, identity of aerial and of ohmic reactions E. M. 1*. is obtained in the coupled circuit whlch receives in perfect accord.

By using as a first approximation the rela tions:

a small fraction of unity there results two couples of roots very close to By using as a second approximation the combined relations LL l-0- L OL exclusive earth propagation is obtained, inasmuch as the ratio becomes negligible for pufi's of power emitted by two sinusoids, almost equal, in contrary sense, in period and in amplitude.

The use as a second approximation of the combined relations and as a third approximation:

LL CR produces a mixed propagation by air and by earth of wave elements having periodically single sinusoidal character, since the general integral of double pure imaginary roots if), so obtained, has the form A sin (ht) +613 sin (ht| The time constant it is actually equal to 60R -\/CL (1 As already hereinbefore stated, the invention can be applied with the ordinary apparatus and arrangement used in wireless telegraphy but its nature and manner of carrying it into effect difier entirely from the methods of syntonization hitherto known.

According to the known methods, syntonization was obtained by the continuous variation of one single electric coe'liicient which was considered to be sufficient for hitting upon one definite relation for one definite period, and the desired result could not be missed; very often a haphazard variation of all the electric coefficients which were in convenient reach, was effected more especially in view of the fact that useful results were often attained although they could not be explained. It will however be seen that no haphazard variation of the various coefficients could possibly hit upon a definite regime governed by three algebraic relations controlling in one definite combination amongst infinite possible ones at least three electric coefficients out of eight, viz :K, M, C, L, R, C, L, R, which are also limited for constructional and other practical reasons.

In order to obtain the regimes it is necessary to take into account, when manipulating each single electric coefficient, the simultaneous variations in the different algebraic relations defining the regime, so as to be able to follow the drift of the phenomena towards the field of approximate regimes wherein it would be easy to find the final fine adjustment increasing the effects it is desired to obtain.

The various operations for obtaining in the first instance the regime fields which should be marked out on the apparatus employed at each station, are as follows The general characteristic equation of 5th degree of a coupled aerial (see page 23 of the Framework of Wireless Telegraphy) can be transformed by the substitution of and be grouped (assuming R to be negligible which is quite accurate in practice) into the form I Y K K BK M K RK mT onrT nn LL m nv from which it will be seen that the sole condition is suflicient for obtaining K K i K RK xHl-x) (Id-170+ (1 +15) +1J (1+$) OTETZ+ITL7$+$Z =O and K K K a I K2 2 .2 2 I t 2 o L 'c TJW YW WCEIT wherein At the station provided with any sort of I BK K quenched spark and having the usual con- 6 T/ /E/ a structional proportions the wireless operator cannot miss the desired result up to this BK K2 point since a continuous manipulation even e W of one electric coefli'cient only, must hit upon the single definite equivalence M K I Therefore what 18 requlred is only a rough I=W approximation of the two regime conditions CL CL, KzRCL making 6 and 6 rather small with respect to unity, together with the single definite relation M2 K Z1T=CTL7B in order toobtain the roots L. Li K K an L L ne n w i" of its own sinusoid, the other wave following in about the same time provided (be positive. The latter can be seen from'its eapression above referred to whilst is only natural:

that is to say q I should halve L and ilsimultanouslyi of two expressions having the same constructional limits, zero and one (see page 35 of"The Framework of VVireless Telegraphy). At this point the impulsive whistle comes into play, by the time being required to charge the primary capacity to the discharge voltage of the spark and by regulation of the resist ance in the supply mains it can conveniently be arranged that it shall have a frequency of 5,000 to 10,000 sparks per second. Now,-

the' wireless operator must look for that particularspot in the field of the whistle that will give the clearest pitch, this corresponding to the exact adjustment of CLzGL together with 7 or M cLzK since the periods thereby almost coincide and the action that takes place is almost according to the generalintegral of regime (1), (2), (3) (see page 27 of The Framework of Wireless Telegraphy).

Having obtained a good clear'whistle as a uidance and the exact equivalence of M CL:K the wireless operator should now try to push the coupling towards one, manipulating C and L but being careful not to touch either of the coeflicients M, C, L except with due mutual compensation, if he wishes to double M, liie .n

its pitch being determined this manner he will hit upon a field of whistle wherein he will notice a sudden fall of the pitch though still quite clear, which means that the third condition of regime namely M zKR has been obtained because the very substantial increase in efficiency of an exact regime having nearly equal 1 (see page 23 of The Framework of Wireless Telegraphy) discharges the primary circuit of its single charge energies much more completely and thus more time is required for re-charging the primary from the mains (see page 31 of The Framework of Wireless Telegraphy).

When searching for the regimes and in order to differentiate between one regime field and another, besides the guidance by the lowest clear pitch of whistle, it is necessary to keep an eye on the ratio of the ampere meter readings in the primary circuit and in the aerial; at a good point of the regime the aerial current will be seen to increase with a kick while the primary decreases. Such comparisons of current readings are sufficient for the guidance to a final adjustment when it is decided to increase the power and to render the whistle too high for audibility by removing the resistance in the supply mains.

it is possible that the aerial without being actually defective does not conveniently allow the expression hd K info m MzOL to those of the triple real root lu a F an on L ,Ru,

and of sinusoidal roots 2L'- or for which (see pages 23, 24, 21 of The Framework of Wireless Telegraphy).

K 1 M 1 2 2 mam W OU-QK The required operations are first to triple (J and L simultaneously and then to push up again the coupling to izi am as whilst keeping M CL':9K constant.

The reception regimes are guided on a transmitted regime with the advantage that the values of coupling between transmission and reception are independent (see pages 82, 33 of The Framework of lVireless Telegraphy). A reception of regime can also be guided on any continuous wave transmission by following a fairly wide interference field which makes itself heard round about a definite regime point which is itself silent, or reduced to a gurgle when the detecting apparatus is in the form of a crystal. That is to say no attempt should be made to im prove the acoustic properties of the interference note as heard through the intermediary of the crystal but the lineof lower pitch should be followed until the interference note. disappears in a greatly reduced region when the employment of other detecting means such as thermic apparatus, heterodyne, Goldschmidt wheel, etc., will reveal an immensely increased received current. Here again the fundamental regime is M CL:K while the manipulation of C and L is free when passing from one wave length to another. The manipulation of C may be effected by a condenser to earth.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is 1. The method of syntonization between two wireless stations whose sending and receiving aerials have a radiation constant K which comprises causing a wave to be propagated in the sending aerial, regulating the capacity C, resistance R, inductance L of each aerial so as to satisfy at all times-the following relationship 1 in R 6L i+ O LKJ; dt=constant where 0: is the aerial current at any given instant of time.

2. The method of syntonization as claimed in claim 1, the additional step of regulating the capacity C, the resistance R and the inductance L of the aerial of the sending station and the capacity C, inductance L, and resistance R of the receiving aerial so that the following relations occur:

CI{:CIIKII; GL CI/LII; CR OIIRII 3. The method of syntonization which comprises varying the aerial current caused to flow 1n an aerial of radiation constant K Whose inductance is L toproduce an aerial"- current a at time 25 such that y Which is the aerial current of a continuous element of the Wave of current variation be defined by K d ir and element of the Wavereaction of the propagated Wave be ide'fined'by' the relation ship 7 Kl: L an such that 2L i f m 5. The method ofsyntonization of aireless station comprising an aerial'with a radiation constant K and a capacity C, resistance R and inductance L and a coupled condenser circuit of capacity C, resistance R, inductance L and Where M is the mutual inductance of the aerial and condenser circuits, comprising regulating the above inductances, capacities, and resistances, and causing the passage of a current i at a time t to flow in the condenser circuit and the current on at time t to flow in the aerial circuit so that the following relations are obtained:

1 cl); (111 ftdt+Rt+L +M -0 and da 1 (10! d M =KR 1 OR 6. ln'the inethod'defined in claim 5, ad-

ditionally regulatingthe resistances and capacities and inductances of the aerial and inductance of the coupled condenser circuit to obtain the following relationships:

and also the following relationships:

i; WEE

7. The method of syntonization of a Wireless station comprising an aerial with a radiation constant K and a capacity C, re-

sistance It and inductance L and a coupled 61av 1. at a and also regulating the said capacities, inductances and resistances so as to obtain the following relationships:

m T onT W lli Where 6 is a small fraction of unity.

8. The method of syntonization of awireless station comprising an aerial With a radiation constant K and a capacity C, resistance R and inductance L and a coupled condenser circuit of capacity C, resistance R, inductance L and Where M is the mutual inductance of the aerial and condenser circuits comprising regulating the above inductances, capacities, and resistances, and causing the passage of a current 2' at a time t to flow in the condenser circuit and the current or at time 25 to flow in the aerial circuit so that the following relations are obtained:

do: 1 ,doz (Z oz MEZ-FFJOZCH'FR Ot+L W-i-Kwand also regulating the said capacities, inductances and resistances so as to obtain the following relationships:

and C R, M KR (1 M oR K a e ga L]7 T CL R0 TEL where 6 is a small fraction of unity, and

and

cuit so that the following relations are obtained:

'- ,fzdi+Rt+L%+M QL dt a l af and also regulating the said capacities, in ductances and resistances so as to obtain the following relationships:

where 0 is a small fraction of unity,

10. In the method defined in claim 9, additionally regulating the above mentioned electrical constants so as to obtain the following relationships:

1 1 M OR CR K a CR LF IT IT C IT L i where 6 is a small fraction of unity.

In testimony whereof I have signed my name to this specification.

ROBERT CLEMENS GALLETTI. 

